Battery voltage checking
Ok ,I have learned not to run a 12 volt battery below 12.1 to maximize lifespan. My question is : do you check voltage under load or at rest. Thanks,Mike
Forum Discussion
MEXICOWANDERER wrote:
I would not OWN the rig that does not have proper instrumentation. How EASY it is to see -17 A/H and -1.6 amps which agrees with the expected load, then I turn in for the night. No advanced calculus just before bedtime. X=I/t - L. Read the meter, it's yes or no.
With off-grid it's always some sort of check-up at sundown. For me it's looking at solar controller display where it shows V at the moment, and says that batteries went into Abs stage and then stayed in Float for 4 or 5 hours on that day. My situation is simple, there are no high loads after sunset.
To know "the whole truth", in addition to present-time SOC (approximate as with any counters of this kind), you would need to know your "usual" overnight consumption. Unless you have a little smelly powerhouse that would auto-start every time when voltage drops too low. Or an audio alarm for low voltage - then you go and crank that thing up.
If somebody wants to sleep well and have no idea where their batteries are going to be by the morning (by no means I'm talking about you Mex here), there is a simple "instrument": turn the loads off and crawl under a good down duvet.
OP - beware of $5 China-direct LED voltmeters on Ebay and Amazon. 99% of them is UNBELIEVABLE junk. It would read with 0.3-0.5V error and would change the readings with time as the circuit warms up.
And, btw, 12.1V in rested battery corresponds to ~30% full. In other words, 70% discharged. Not good.
